Grade 12 student William Swinimer, 19, is due to return to class Monday after a five-day suspension last week by the Forest Heights Community School in Nova Scotia, west of Halifax.
He had been wearing the T-shirt every day and was cautioned before and given a 12-day in-school suspension earlier this year.
School Board Superintendent Nancy Pynch-Worthylake told The (Halifax) Chronicle-Herald the T-shirt could be offensive to those with other beliefs.
"If it said 'My Life is Wasted Without Jesus,' that would be fine," because that would be more personal, she said.
However, Swinimer said he's not backing down when he returns to school.
"They say that it's hate speech and that it hurts people's feelings, but I don't hate anybody," he said. "I'm going to stand up for my rights as a Canadian citizen."
The school board is consulting with a human rights expert on the matter, the newspaper said.